Legend:

This approach, often called "native virtualization", is different from mere emulation. With that approach, as performed by programs such as [http://bochs.sourceforge.net/ BOCHS], guest code is not allowed to run directly on the host. Instead, every single machine instruction is translated ("emulated"). While emulators theoretically allow running code written for one type of hardware on completely different hardware (say, running 64-bit code on 32-bit hardware), they are typically quite slow. Virtualizers such as !VirtualBox, on the other hand, can achieve near-native performance for the guest code, but can only run guest code that was written for the same target hardware (such as 32-bit Linux on a 32-bit Windows host).

6

6

7

!VirtualBox is also different from so-called "paravirtualization" solutions such as [http://www.xensource.com/xen/ Xen], which require that the guest operating system be modified.

7

!VirtualBox is also different from so-called "paravirtualization" solutions such as [http://www.xen.org Xen], which require that the guest operating system be modified.